X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 22 Jan 2008 10:41:43 -0500 Message-ID: X-Original-Return-Path: Received: from mta9.adelphia.net ([68.168.78.199] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTP id 2682653 for lml@lancaironline.net; Mon, 21 Jan 2008 21:26:13 -0500 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.199; envelope-from=glcasey@adelphia.net Received: from [75.82.216.175] by mta9.adelphia.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20080122022532.QDHJ14013.mta9.adelphia.net@[75.82.216.175]> for ; Mon, 21 Jan 2008 21:25:32 -0500 Mime-Version: 1.0 (Apple Message framework v752.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-2--676767791 X-Original-Message-Id: <658E73B8-5C22-4F3E-A9E0-EDC1B581C277@adelphia.net> From: Gary Casey Subject: Re: Pressurized Injectors X-Original-Date: Mon, 21 Jan 2008 18:25:31 -0800 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.752.2) --Apple-Mail-2--676767791 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed In the pursuit of over-analysis of everything worthwhile I have been attempting to get data that might quantify the benefit of increasing the air pressure drop across the injectors (aka pressurizing the injectors). I ran a number of tests and analyzed the two that seemed to have the most consistent data. I flew at 11,500 feet at Wide Open Throttle (WOT) first and then at the same condition except that the throttle was closed enough to reduce Manifold Absolute Pressure (MAP) by approximately 1 inch. Many of the calculated results were inconclusive. For instance, the peak speed and peak MPG were closely correlated to the power regardless of throttle position. The MPG was close to a straight line, rising with reduced fuel flow. LOP the same fuel flow produced nearly the same speed. I also calculated an "Coefficient of Effectiveness" (Ke), which was MPG times MPH. While MPG continues to rise when the mixture is leaned, Ke leveled off and slightly peaked just LOP. Conclusion is that if you want to get someplace in a hurry (why have a Lancair if you don't!) and are willing to pay 10% more in fuel to get there 10% faster, then there is not point in running very much lean of peak - just slightly lean is good enough. Leaner than that and the speed starts to drop significantly (turbocharged drivers ignore the preceding conclusion). What was interesting was the slope of the EGT vs. fuel flow LOP and the variation in that number from cylinder to cylinder. With the throttle slightly closed (more air flow through the injectors) the slope was 19% higher and the variation was reduced by 32%. Also, the fuel distribution from cylinder to cylinder went from a range of 2.8% to 0.6%, although I don't trust the lower number since the standard deviation only changed from 1.1% to 0.6%, still significant, but not as dramatic. Why would the slope be higher? I'm thinking there is less cycle-to cycle fuel delivery variation, creating a sharper and higher peak temperature and therefore a steeper slope. What does all this mean? That I have too much time on my hands, maybe? I don't know the actual pressure drop across the injectors at WOT, so I don't know how much improvement in atomization I could have expected. I think the data suggests there could be a slight but real improvement in engine operation when running LOP if there can be a positive pressure maintained across the injectors. Gary Casey > > From: Sky2high@aol.com > Date: January 20, 2008 4:22:29 PM PST > To: lml@lancaironline.net > Subject: Re: [LML] Pressurized Injectors > > > > > In a message dated 1/20/2008 12:49:20 P.M. Central Standard Time, > douglasbrunner@earthlink.net writes: > A while ago there was a thread on the effect of pressurized > injectors on fuel atomization. It was suggested that pressurizing > the injectors improves fuel atomization and leads to a smoother > running engine LOP at high altitudes. > > Recently, we ran tests to see what effect the use of Ram Air had on > smoothness of operation at high altitude. > > Engine: IO-550N, 10:1 compression, ram air, magnetos, GAMI > injectors, GAMI spread of .2 gallons > Conditions: Altitude = 17,500, OAT = 1 C > > Without Ram Air (MAP = 15.2) the engine ran smoothly down to about > 60 deg LOP or 8.8 gal/hr > > With Ram Air (MAP = 16.3) the engine only ran smoothly to Peak or > 11.2 gal/hr > > The only difference between these two settings (that I can think > of) is that in the first, ambient air pressure is probably > slightly above manifold pressure (accounting for the filter) - > which means the injector is pressurized very slightly. In the > second, ambient pressure is probably about 1.0 less than manifold > pressure (accounting for ram effect) so pressurization of the > injector is reversed. This would seem to confirm the fact that > unpressurized injectors reduces fuel atomization and makes for a > rougher running engine LOP at altitude. > > I would like to run smoothly LOP at altitude using ram air. It > seems to me that I can go ahead and pressurize my injectors by > running tubes off the ram air tube to the injectors and using turbo > injectors. (Is Mike Mahar still selling this setup?) Not sure > that I want to go to the time, trouble and expense to do this though. > > I am also wondering if using a "hotter" spark from Electronic > Ignition would improve the problem. (I would try to use an > Electronic Ignition system that had the same advance as mags) > > Your thoughts? > Doug, > > Well, you asked, so................. > > Let's try to get a common understanding of the contribution of > components first. Remember that good combustion is a result of the > right amount of air and fuel (A/F ratio) and something to ignite > the mixture. Work is performed at a reasonable time in the > combustion cycle by having the combustion event reach some > appropriate state of completion( good pressure) at a certain range > of motion of the piston after TDC, say around 16 degrees. Each > time you change one of the combustion components, it affects the > rest. Higher compression ration, fuel octane, spark effectiveness, > timing, yada, yada, yada. > > At some point, after the engine was broken in, the baffling was set > and ram system built, a Gami lean test was performed and used to > get injectors that were sized to deliver A/F ratios so that each > cylinder was receiving the fuel, air and spark that resulted in > delivering fairly equal amounts of power as measured by reaching > peak within a narrow fuel delivery range. Thus, LOP the engine ran > smoothly. > > Now, a component was changed without recording all the data > necessary to analyze the results. It would be useful to run the > GAMI lean test again, with and without RAM air, since it appears > that the smoothness is gone because the cylinders are producing > different power. One thing that the ram set-up may do is cause an > unusual flow thru the throttle body, thus altering the A/F in some > cylinders. Perhaps the airflow is altered in the cooling plenum > that provides air to the injectors and there could be some effect. > > The major benefit of providing controlled air equally to all the > injectors reduces the possible effect of peculiar air flow in the > cooling chamber on atomization. Be careful - the GAMI injectors > were tuned to your engine as it was operating when the GAMI lean > test was performed. Changing to shrouded injector bodies may again > change atomization and the A/F ratio in each cylinder and not > result in an improvement. The benefit of supplying air to the > injector at or above the MAP (I don't know what you mean by ambient > pressure) is that there is no detriment to atomization. > > Electronic ignitions do not just provide a "hotter" spark. They > also provide a spark every time it is needed (some mags miss > although you wouldn't notice it merely by feel), a longer more > powerful spark to insure the mixture is ignited even if it isn't > the best mixture for ignition and, they can adjust the timing to > deliver the same power for less fuel (or more power for the same > fuel) at different power settings as determined by RPM and MAP. > Electronic ignitions may help your engine be inherently smoother, > depending. Without the timing adjustments, you are assuming the > mag timing is right even though you have increased the CR by quite > a bit. High power performance might be improved by using less than > 25 DBTDC. > > You have started to experiment with ram air to achieve better > performance (for free) from an engine upon which you spent many > dollars for high CR pistons and GAMI injectors to get a high level > of performance. You have to be willing to spend more money and time > on the further experimentation necessary to keep things moving > towards more optimal performance. It seems you had a good > configuration where everything was reasonably optimal (filtered > air, GAMI, etc.) and the next step (free ram air) seemed simple > except that the balance in your engine has been upset. > > Welcome to the world of tweaking, resulting in effects similar to > those of the snowball at the top of the avalanche area. > > Scott Krueger AKA Grayhawk > Lancair N92EX IO320 SB 89/96 > Aurora, IL (KARR) > > Pilot not TSO'd, Certificated score only > 70%. --Apple-Mail-2--676767791 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 In the pursuit of over-analysis of everything worthwhile I have been = attempting to get data that might quantify the benefit of increasing the = air pressure drop across the injectors (aka pressurizing the injectors). = =A0I ran a number of tests and analyzed the two that seemed to have the = most consistent data. =A0I flew at 11,500 feet at Wide Open Throttle = (WOT) first and then at the same condition except that the throttle was = closed enough to reduce Manifold Absolute Pressure (MAP) by = approximately 1 inch. =A0Many of the calculated results were = inconclusive. =A0For instance, the peak speed and peak MPG were closely = correlated to the power regardless of throttle position. =A0The MPG was = close to a straight line, rising with reduced fuel flow. =A0LOP the same = fuel flow produced nearly the same speed. =A0I also calculated an = "Coefficient of Effectiveness" (Ke), which was MPG times MPH. =A0While = MPG continues to rise when the mixture is leaned, Ke leveled off and = slightly peaked just LOP. =A0Conclusion is that if you want to get = someplace in a hurry (why have a Lancair if you don't!) and are willing = to pay 10% more in fuel to get there 10% faster, then there is not point = in running very much lean of peak - just slightly lean is good enough. = =A0Leaner than that and the speed starts to drop significantly = (turbocharged drivers ignore the preceding conclusion).

What was interesting was = the slope of the EGT vs. fuel flow LOP and the variation in that number = from cylinder to cylinder. =A0With the throttle slightly closed (more = air flow through the injectors) the slope was 19% higher and the = variation was reduced by 32%. =A0Also, the fuel distribution from = cylinder to cylinder went from a range of 2.8% to 0.6%, although I don't = trust the lower number since the standard deviation only changed from = 1.1% to 0.6%, still significant, but not as dramatic. =A0Why would the = slope be higher? =A0I'm thinking there is less cycle-to cycle fuel = delivery variation, creating a sharper and higher peak temperature and = therefore a steeper slope.

What does all this mean? = =A0That I have too much time on my hands, maybe? =A0I don't know the = actual pressure drop across the injectors at WOT, so I don't know how = much improvement in atomization I could have expected. =A0I think the = data suggests there could be a slight but real improvement in engine = operation when running LOP if there can be a positive pressure = maintained across the injectors.

Gary Casey = =A0

Date: January 20, 2008 4:22:29 PM = PST
To: lml@lancaironline.net
Subject: Re: [LML] Pressurized = Injectors

= =
=A0
=A0
In a message dated 1/20/2008 12:49:20 = P.M. Central Standard Time, douglasbrunner@earthlink.net<= /a> writes:
A=A0 while ago there was a thread on the = effect of pressurized injectors on fuel atomization.=A0 It was suggested = that pressurizing the injectors improves fuel atomization and leads to = a smoother running engine LOP at high altitudes.
=
=A0
Recently, we ran tests to see what effect the = use of Ram Air had on smoothness of operation at high = altitude.
=A0
=
Engine:=A0IO-550N, 10:1 = compression, ram air, magnetos, GAMI injectors, GAMI spread of .2 = gallons
Conditions: Altitude = =3D=A017,500, OAT=A0=3D 1 = C
=A0
=
Without Ram Air (MAP =3D 15.2) the = engine ran smoothly down to about 60 deg LOP or 8.8 = gal/hr
=A0
=
With Ram Air (MAP =3D 16.3) the = engine only ran=A0smoothly to Peak or 11.2 gal/hr
=
=A0
The only=A0difference between these two = settings (that I can think of)=A0=A0is that in the first, ambient air = pressure is probably=A0slightly=A0above manifold pressure (accounting = for the filter) - which means the injector is pressurized very = slightly.=A0In the second, ambient pressure is probably about=A01.0 less = than manifold pressure (accounting for ram effect) so pressurization = of the injector is reversed.=A0 This would seem to confirm the fact = that=A0unpressurized injectors reduces=A0fuel atomization and makes for = a rougher running engine LOP at altitude.
=A0
I would like to run smoothly=A0LOP at altitude using ram = air.=A0 It seems to me that I can go ahead and pressurize my injectors = by running tubes off the ram air tube to the injectors and using turbo = injectors.=A0 (Is=A0Mike Mahar still selling this setup?)=A0 Not sure = that I want to go to the time, trouble and expense=A0to do this = though.
=A0
I am also wondering if using a = "hotter" spark from Electronic Ignition would improve the problem.=A0 = (I would try to use an Electronic Ignition system that had the same = advance as mags)
=A0
Your = thoughts?
Doug,
=A0
=
Well, you asked, so.................
=A0
=
Let's try to get a common understanding of=A0the contribution of = components first.=A0 Remember that good combustion is a result of the = right amount of air and fuel (A/F ratio) and something to ignite the = mixture.=A0 Work is performed at a reasonable time in the = combustion=A0cycle by having the combustion event reach some appropriate = state of completion( good pressure) at a certain range of motion of the = piston after TDC, say around 16 degrees.=A0 Each time you change one of = the combustion=A0components, it affects the rest. Higher compression = ration, fuel octane, spark effectiveness, timing, yada, yada, = yada.
=A0
At some point, after the engine was = broken in, the baffling was set and ram system built, a=A0Gami lean test = was performed and used=A0to get=A0injectors that were sized to deliver = A/F ratios so that each cylinder was receiving the fuel, air and spark = that resulted in delivering fairly equal amounts of power as measured by = reaching peak within a narrow fuel delivery range.=A0 Thus, LOP the = engine ran smoothly.
=A0
Now, a component was = changed without=A0recording all the data necessary to analyze the = results.=A0 It would be useful to run the GAMI lean test again, with and = without RAM air, since it appears that the smoothness is gone because = the cylinders are producing different power.=A0 One thing that the ram = set-up may do is cause an unusual flow thru the throttle body, thus = altering the A/F in some cylinders.=A0=A0 Perhaps the airflow is altered = in the cooling plenum that provides air to the injectors and there could = be some effect.
=A0
The major benefit of providing = controlled air equally to all=A0the injectors reduces the possible = effect of peculiar air flow in the cooling chamber on atomization.=A0 Be = careful - the GAMI injectors were tuned to your engine as it was = operating when the GAMI lean test was performed.=A0 Changing to shrouded = injector bodies may again change atomization and=A0the A/F ratio in each = cylinder and not result in an improvement.=A0 The benefit of supplying = air to the injector at or above the MAP (I don't know what you mean by = ambient pressure) is that there is no detriment to atomization.
=
=A0
Electronic ignitions do not just provide a "hotter" = spark.=A0 They also provide a spark every time it is needed (some mags = miss although you wouldn't notice it merely by feel), a longer more = powerful spark to insure the mixture is ignited even if it isn't the = best mixture=A0for ignition and, they=A0can adjust the timing to deliver = the same power for less fuel (or more power for the same fuel) at = different power settings as determined by RPM and MAP.=A0 Electronic = ignitions may=A0help your engine=A0be inherently smoother, depending.=A0 = Without the timing adjustments, you are assuming the mag timing is right = even though you have increased the CR by quite a bit.=A0 High power = performance might be improved by using less than 25 DBTDC.
=
=A0
You have started to experiment with ram air to = achieve better performance (for free)=A0from an engine upon which=A0you = spent many dollars=A0for high CR pistons and GAMI injectors to get a = high level of performance.=A0You have to be willing to spend more money = and time=A0on the further experimentation necessary to keep things = moving towards more=A0optimal performance.=A0 It seems you had a good = configuration where everything was reasonably optimal (filtered air, = GAMI, etc.) and=A0the next step (free ram air) seemed simple except that = the balance in your engine has been upset.=A0
=A0
=
Welcome to the world of tweaking, resulting in effects similar to = those of the snowball at the top of the avalanche area.
=
=A0
Scott Krueger AKA Grayhawk
Lancair = N92EX IO320 SB 89/96
Aurora, IL (KARR)

Pilot not TSO'd, = Certificated score only > = 70%.

= --Apple-Mail-2--676767791--